1. Field of the Invention
The subject matter of this invention relates to miniature circuit breakers and in particular to shunt trip devices for miniature circuit breakers.
2. Description of the Prior Art
Miniature circuit breakers with remotely controlled solenoid coils for turning the circuit breaker on and off are well know in the art. An Example of this may be found in U.S. Pat. No. 4,625,190 entitled "Remotely Controlled Solenoid Operated Circuit Breaker" by Wafer et al., issued Nov. 25, 1986; and U.S. Pat. No. 4,725,799 entitled "Circuit Breaker with Remote Control" by Bratkowski et al., issued Feb. 16, 1988. The solenoid in the aforementioned circuit breaker may be energized to trip the circuit breaker by way of a plunger. However actuation of a circuit breaker into the tripping mode with the utilization of a plunger requires a relatively large circuit breaker because of the space taken up by the solenoid and plunger.
Smaller, miniature circuit breakers not having solenoid operated tripping mechanism are also well known the art. An example of this can be found in U.S. Pat. No. 3,849,747 entitled "Circuit Breaker with Handle Indicating Means" issued to Mrenna et al., on Nov. 19, 1974; and U.S. Pat. No. 3,959,754 entitled "Circuit Breaker with Improved Trip Means" issued to Mrenna on May 25, 1996. These circuit breakers are generally relatively narrow and may be, for example, one-half inch wide. They do not have to accommodate the previously described solenoids. They do perform the normal thermal tripping operation by utilizing a bimetal actuator for lower level overloads and a magnetic armature for higher level overloads.
A shunt trip device for a miniature circuit breaker may include a non-overload actuable miniature circuit breaker case that is stacked side-by-side with one or more operating circuit breakers. The shunt trip coil is disposed on the non-actuable circuit breaker magnetic core and is interconnected with external shunt trip actuating leads. There is no thermal or magnetic tripping capability in the non-actuable circuit breaker coil. All of the side-by-side circuit breakers have a common trip mechanism arm, rotating shaft so that if one is tripped open the others open automatically whether the tripping action is caused by a thermal trip in one of the active circuit breakers, or a magnetic trip in one of the active circuit breakers or a shunt trip in the shunt trip device.
It would be advantageous if a shunt trip device could be found and utilized within a relatively narrow, for instance 1/2 inch, miniature circuit breaker case which is ganged in side-by-side relationship with actual circuit breakers. It would be further advantageous, if the basic circuit breaker mechanism could be quickly modified to produce the shunt trip device without the necessity of having to design a completely separate shunt trip mechanism.